The present invention relates to angioplasty and, in particular, to a dilatation balloon catheter.
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating types of vascular diseases. In particular, angioplasty is widely used for opening stenoses in the coronary arteries. It is also used for treatment of stenoses in other parts of the vascular system.
A common form of angioplasty makes use of a dilatation catheter which has an inflatable balloon at its distal end. With the aid of fluoroscopy, a physician guides the catheter through the vascular system until the balloon is positioned across the stenosis. The balloon is then inflated by supplying fluid pressure through an inflation lumen to the balloon. Inflation of the balloon causes stretching of the artery and a pressing of the lesion into the artery wall to reestablish acceptable blood flow.
It is a common practice to employ a guide wire to establish the path to the stenosis. The dilatation catheter is then fed over the guide wire until the balloon is positioned within the stenosis. One advantage resulting from the use of a guide wire is the ability to maintain the desired position within the vascular system when replacing the catheter--as when a larger or smaller balloon is desired, for example. One disadvantage of many catheter systems employing a guide wire (often referred to as "over-the-wire" catheters), is the need to accommodate the guide wire within the catheter. This has often been accomplished through the provision of a guide wire lumen separate from that which delivers fluid pressure for balloon inflation/deflation. Such separate lumens result in larger catheter shaft diameters than are typical for fixed wire catheters.
In U.S. Pat. No. 5,032,113 by Matthew Burns issued Jul. 16, 1991, and in U.S. Pat. No. 5,035,705 by Matthew Burns issued Jul. 30, 1991, there are disclosed "innerless" over-the-wire catheters which feature a shaft with a single lumen for both inflation/deflation and the guide wire. The innerless catheters offer the advantages of an over-the-wire catheter without requiring a large diameter shaft. The disclosures of these two commonly-owned patents are hereby incorporated by reference.